Here in Switzerland I do a lot of mountainous roads. And imo it's the best to enjoy a crossfire!

My advice to you: Just go and find out! The car is flexible and indulgent. With ESP/ABS you got a good guardian angel It really needs a lot until you can hear the tires wheeze (or how you call it in english).

That's how I do uphill (if my girl allows): Full speed toward the hairpin curve. Shortly before throttle and hard breaking, into the curve with released breaks but slight acceleration and after 75% step on it!! ESP might light up, but consider this as onboard entertainment...

If you have AT use Autostick! Before the curve while breaking quickly shift down to keep high rpm. After getting used to Autostick it's real fun and you control the engine and perfect shifting.
But as I said above, go and find out yourself. I can't await my next trip to the mountains... Steep and curvaceous - that's what makes a xf adorable!